1. Field of the Invention
This invention relates to Hall effect devices and particularly to an encapsulation structure for packaging Hall effect devices. While not necessarily limited thereto, this invention is contemplated for use with contactless key mechanisms using a solid state switch employing the Hall effect.
2. Description of the Prior Art
Contactless switches for use in keyboards and elsewhere are well-known in the art. One type of contactless switch utilizes a Hall effect device. In such switches, a magnetic activator, typically one or more permanent magnets, is designed to be moved relative to a Hall effect magnetic field sensing element to induce an output signal from the Hall effect sensing element. Several such switches utilizing the Hall effect are shown in U.S. Pat. Nos. 3,858,145; 3,873,957; 3,882,337; 4,054,861; and 4,061,988.
As seen in these patents, contactless switches employing the Hall effect comprise a variety of different configurations. Most of these involve rather intricate mechanical structures accommodating the Hall effect sensing element and its leads, the magnets which activate the Hall effect element and the magnetic conductor materials which participate in the magnet circuit leading to and from the activation magnets and including the Hall effect sensing element. Accordingly, many of these structures require a relatively large amount of space and their assembly is expensive and time consuming.
One step which has been taken to simplify construction of devices incorporating Hall effect sensing elements is to mount the small semiconductor chips incorporating the sensing elements on long, thin strips, resembling conventional photographic film strips. This mounting scheme offers two kinds of efficiency and economy. First, the bare Hall sensing element semiconductor chip with its leads can be cheaply and quickly given a suitable protective encapsulation and packaging form which leads to convenience in handling the Hall sensing elements from the point of manufacture and/or encapsulation to the place where the sensing elements are incorporated into contactless switches or other applications. Second, handling the large numbers of Hall sensing elements involved in mass production of contactless switch keyboards or other applications is facilitated by incorporating these elements on a long continuous medium which can be easily controlled and metered through automated assembly equipment.